In the world of BBK/BRNK, It’s been ten years since Azuma Kazuki has been in Japan, and upon his arrival he is taken prisoner by a group of armed men. Azuma is saved by his childhood friend, Kogane Asabuki, thanks to a living weapon she wields on her right hand, known as a Bubuki. Learning about these weapons, Azuma becomes a Bubuki wielder himself and sets out on a journey.